Development of Thermokinetic Tools for Phase Transformation Studies of Zr Alloys for Both In-Service and LOCA Conditions

Thermodynamic and kinetic calculations are commonly used for forecasting phase transformations in multi-component alloys as a function of composition, temperature and time. They also turn to be very useful for new alloys design. Thus, in the framework of the qualification of existing industrial alloys and the development of new ones (Cr coated Zr alloys for instance), a new generation of thermodynamic database has been developed thanks to the systematic use of ab initio calculations. Indeed, DFT (Density Functional Theory) calculations are significant for the determination of formation enthalpies of stable and metastable phases. Moreover, SQS method (Special Quasirandom Structure) is used for the prediction of fcc, bcc and hcp mixing enthalpies in binary solid solutions. software (free software for multicomponent equilibrium calculations). This tool has been developed to simulate with accuracy oxide growth and oxygen diffusion into the alloy during hightemperature isothermal oxidation of Zr alloys. The recent developments have been dedicated to the simulation of high-temperature transients showing a good agreement with experimental data.